Supercurrents through single-walled carbon nanotubes

Proximity-induced superconductivity in single-walled carbon nanotubes below 1 kelvin, both in a single tube 1 nanometer in diameter and in crystalline ropes containing about 100 nanotubes, was observed. The samples were suspe nded between two superconducting electrodes, permitting structural study in a transmission electron microscope. When the resistance of the nanotube ju nction is sufficiently low, it becomes superconducting and can carry high s upercurrents. The temperature and magnetic field dependence of the critical current of such junctions exhibits unusual features related to their stron g one-dimensional character.